Question

在我的iOS应用中，我必须对UIImage进行一些修改，例如在其上添加水印。之后，我想使用原始元数据保存图像，但如果我尝试使用writeImageDataToSavedPhotosAlbum:metadata:completionBlock:，则生成的图像中没有任何内容。

由于我必须修改图像，因此我必须使用以下方法传递NSData metadata:部分：UIImageJPEGRepresentation(UIImage *, float)。

在保存图像之前，元数据就像：

Meta: {
    ApertureValue = "2.526068811667587";
    BrightnessValue = "-1.807443054797895";
    ExposureMode = 0;
    ExposureProgram = 2;
    ExposureTime = "0.05882352941176471";
    FNumber = "2.4";
    Flash = 16;
    FocalLenIn35mmFilm = 33;
    FocalLength = "4.12";
    ISOSpeedRatings =     (
        800
    );
    LensMake = Apple;
    LensModel = "iPhone 5c back camera 4.12mm f/2.4";
        LensSpecification =     (
        "4.12",
        "4.12",
        "2.4",
        "2.4"
    );
    MeteringMode = 3;
    PixelXDimension = 3264;
    PixelYDimension = 2448;
    SceneType = 1;
    SensingMethod = 2;
    ShutterSpeedValue = "4.058917734171294";
    WhiteBalance = 0;
    "{GPS}" =     {
        Altitude = "147.9932";
        DOP = "76.42908";
        Latitude = "45.7398";
        LatitudeRef = N;
        Longitude = "126.6266";
        LongitudeRef = E;
        TimeStamp = "2013:12:23 08:45:30";
    };

那么，这里有什么问题？

Answer 1

试试这个，

UIImage *newImage = self.yourOriginalImage;

UIImage *anotherImage = @"waterMark.png";
CGImageRef imageRef = anotherImage.CGImage;

CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(imageRef),
                                        CGImageGetHeight(imageRef),
                                        CGImageGetBitsPerComponent(imageRef),
                                        CGImageGetBitsPerPixel(imageRef),
                                        CGImageGetBytesPerRow(imageRef),
                                        CGImageGetDataProvider(imageRef), NULL, false);

CGImageRef maskedImage = CGImageCreateWithMask([newImage CGImage], mask);
self.imageView.image = [UIImage imageWithCGImage: maskedImage];

Answer 2

假设您有一个名为myEditedImage的UIImage以及名为“metadata”的NSDictionary（或NSMutableDictionary ...）中的元数据：

ALAssetsLibrary *library;
ALAssetsLibraryWriteImageCompletionBlock completionBlock = ^(NSURL *assetURL, NSError *error) {};
float compressionLevel = 0.75; // Or whatever you want
NSData *dataIn = UIImageJPEGRepresentation(myEditedImage, compressionLevel);
[library writeImageDataToSavedPhotosAlbum: dataIn
     metadata: metadata
     completionBlock:completionBlock];

如何用原始元数据保存修改后的UIImage？

2 个答案: